Question

Consider a long tube of 25 mm outside diameter (do) and of 20 mm inside diameter (di) twisted about its longitudinal axis with a torque T of 45 N-m. The polar moment of inertia of the hollow tube is-

• A. 22641 mm⁴
• B. 36980 mm⁴
• C. 18933 mm⁴
• D. 27271 mm⁴

Answer 1

Answer:

A. 22641 mm⁴

Given: D = 25 mm, d = 20 mm $J=\frac{\pi(D ^ 4 - d ^ 4)}{32}=\frac{\pi(25 ^ 4 - 20 ^ 4)}{32} = 22641mm ^ 4$